Leveraging artificial intelligence to differentiate benign from malignant biliary strictures: A step toward precision diagnosis

Table 3 Advanced modalities for biliary strictures

Modality	Sensitivity range, %	Specificity range, %	Advantages/limitations	Notes
Intraductal ultrasound[33-35]	93-97	79-90	Pros: Real-time wall-layer/T-staging, superior for proximal strictures. Cons: Probe insertion issues, limited N-staging, advanced tumors	Large retrospective cohorts (n = 193; n = 379) using histopathology or long-term follow-up as reference standards[34,35]
Cholangioscopy directed biospy[28,36,37]	58-86	90-100	Pros: Direct visualization, targeted sampling in proximal lesions. Cons: Costly equipment, expertise required, distal limitations	Multicenter retrospective SpyGlass DS™ cohort (n = 206)[36]; pooled evidence from systematic review and meta-analysis extracted data from 15 studies (n = 539) by Badshah et al[37]
EUS + FNA[38-40]	76-94	90-97	Pros: Excellent for distal strictures and mass lesions, deeper access. Cons: Perihilar challenges, lower yield without mass. Significant impact on surgical decision-making	Meta-analysis (6 studies, n = 497)[38] and prospective cohorts (n = 50)[39]; n = 44[40] confirm high diagnostic accuracy of EUS-FNA, particularly for extraductal lesions > 1.5 cm. The gold standard was surgery or 6 months follow up
EUS guided FNA + ERCP guided TA[38,39]	86-98	98-100	Pros: Maximizes yield in the same session, reduces false negatives. Cons: Procedural time and risk increase, resource-intensive	Systematic review and meta-analysis of same-session procedures (6 studies, n = 497) demonstrated an accuracy of 96.5%, superior to either modality alone, including hilar, perihilar, and distal strictures[38]. Prospective comparative study (n = 50) showed combined sensitivity 97.9% and accuracy 98%, significantly reducing false negatives[39]. The gold standard was surgery or 6 months follow up
EUS + FNB[41,42]	85-98	90-100	Pros: Better tissue yield than FNA, ideal for distal strictures. Cons: Seeding risk, operator-dependent	Prospective multicenter cohort (n = 465) showed superior tissue core yield and histologic accuracy with 22G FNB (99%) vs FNA (61%), with reduced blood contamination; combined analysis reached 100% diagnostic accuracy[41]
EUS guided FNB and ERCP guided tissue acquisition[43,44,60]	83-100	95-100	Pros: EUS-FNB serves as a first-line or complementary tool for diagnosing indeterminate biliary strictures, offering superior sensitivity (83%-98%) over ERCP sampling, especially for distal/extrahepatic lesions without visible masses. Cons: Increased procedural time/risk, dual expertise needed	Retrospective BS cohort (n = 51) with surgical histology or radiologic/clinical follow-up as gold standard showed higher accuracy with same-session EUS-FNB + ERCP (83.3% sensitivity; 87.5% accuracy; 100% specificity) vs either alone[43]. Sensitivity drops to 56%-75% with stents or hilar location due to access challenges[44]
pCLE[45]	75-80	80-85	Pros: In vivo histology, real-time neoplasia detection, improved with Paris Classification. Cons: Probe fragility, steep learning curve, limited availability, high cost	Validation study of the Paris Classification using 40 pCLE sequences (19 inflammatory, 6 benign, 15 malignant indeterminate biliary strictures) demonstrated improved specificity with maintained overall accuracy (approximately 82%). The gold standard was histopathology or clinical follow-up. Interobserver agreement was fair (κ = 0.37). Lesions involved indeterminate bile duct strictures, primarily the extrahepatic biliary tree during ERCP-based evaluation
OCT/VLE[46,47]	79	69	Pros: Microstructural imaging of desmoplasia excels in tight strictures. Cons: Interpretive variability, limited availability, large RCTs needed to confirm its clinical impact	Prospective ERCP-OCT study (n = 37 biliary strictures; 19 malignant, 16 benign) using histology/EUS-FNA/surgery or ≥ 12-months follow-up as reference standard showed sensitivity 79% and specificity 69% (≥ 1 criterion); specificity 100% when both criteria were required. Combined with brushings, increased sensitivity to 84%[47]

EUS: Endoscopic ultrasound; FNA: Fine needle aspiration; FNB: Fine needle biopsy; ERCP: Endoscopic retrograde cholangiopancreatography; TA: Tissue acquisition; BS: Biliary stricture; pCLE: Probe-based confocal laser endomicroscopy; OCT: Optical coherence tomography; VLE: Volumetric laser endomicroscopy.